Fix use of a dangling pointer for Python breakpoint objects
When a Python script tries to create a breakpoint but fails to do so, gdb.Breakpoint.__init__ raises an exception and the breakpoint does not exist anymore in the Python interpreter. However, GDB still keeps a reference to the Python object to be used for a later hook, which is wrong. This commit adds the necessary cleanup code so that there is no stale reference to this Python object. It also adds a new testcase to reproduce the bug and check the fix. 2016-06-25 Pierre-Marie de Rodat <email@example.com> gdb/ * python/py-breakpoint.c (bppy_init): Clear bppy_pending_object when there is an error during the breakpoint creation. gdb/testsuite * gdb.python/py-breakpoint-create-fail.c, gdb.python/py-breakpoint-create-fail.exp, gdb.python/py-breakpoint-create-fail.py: New testcase.